1. Field of the Invention:
The present invention relates to a color image sensing apparatus having an improved automatic white balance adjustment device.
2. Description of the Prior Art:
In color television cameras, particularly, portable television cameras for home use, the small-sized, light-weight and high-performance cameras have been developed based on the recent advance of electric circuit technology. Particularly, according to the realization of non-adjustment of a circuit and automation of operation, color television cameras with which any person having no special knowledge can easily take a photograph, have been manufactured and have come into wide use.
The most popular error in photography by such a color television camera is color adjustment failure particularly, white balance adjustment. Unless a color television camera is adjusted in such a way that when a white object is photographed the ratio of components of the three primary colors, that is, red (R), green (G) and blue (B), which are contained in an output television signal, is 1:1:1, the quality of color-reproduction of an image to be reproduced on a television screen is decreased. Therefore, white balance adjustment for adjusting color signal gains in accordance with illuminating light at a place to be photographed prior to photography is necessary. Heretofore, the white balance adjustment was effected such that an operator directly adjusted a circuit constant or an optical filter by using a monitor television or a waveform monitor or the like. Recently, automatic adjustment, the so-called automatic white balance adjustment, has been effected. However, in the conventional automatic white balance adjustment, there are large errors in some conditions of use and the possiblility of erroneous operation. When an average person effects the adjustment, a satisfactory picture cannot be obtained in many cases. The particular drawbacks are as follows:
(1) An operator is apt to forget to set white balance adjustment.
(2) A large error occurs unless white balance adjustment is set for a white object.
(3) When the illumination condition changes after setting, white balance adjustment does not follow unless resetting is effected.